Grand piano construction



Dec. 10, 1968 HARUHISA NODA 2 Sheets-Sheet 1 Filed Dec. 15, 1966 MWMM INVENTOR. M m

1958 HARUHISA NODA 3,415,151

GRAND PIANO CONSTRUCT ION Filed Dec. 15. 1966 2 Sheets-Sheet 2 \WMM INVENTOR.

United States Patent 5 Claims. (Cl. 84-186) This invention relates to the construction of grand pianos wherein braces, wooden structure and metal frame are so arranged that sounds over the entire scale can be uniformly generated and that the generation of sounds by improving the volume and quality of tones in the treble region and higher harmonic components of bass tones may be improved.

This invention relates to the construction of pianos and more particularly relates to the construction of an improved grand piano capable of generating a well-balanced sound over the entire scale of the piano.

The basic framing of a grand piano consists of a wooden inner rim wherein several wooden braces are disposed and which rim is connected at both ends by a cross block, and a cast metal frame mounted above this rim-brace wooden assembly.

To the inner rim is connected the cross block which connects the both ends of the inner rim. T o the cross block are connected for example four radially extending braces as well as a single treble side brace which extends from a portion close to the treble side end of the cross block to an inwardly curved portion of the inner rim, said radially extending braces extending from a slightly bass side portion with respect to a central portion of the cross block radially toward the inner surface of the inner rim. Such radially extending braces are connected to a beam which extends over the length between the inner opposing surface of the inner rim in a direction parallel to the cross block.

In a conventional grand piano, these braces are arranged at such locations and in such number that are optimum in view of the theory of structures. It is known that the braces on the other hand play an important role in transmitting the vibrations produced by piano strings to the entire structure of the piano to produce a sound of good tonal quality. However, since the treble side brace is mounted separately from the other braces, the transmission of vibration becomes non-uniform between the sound produced in the bass and middle regions and that produced in the treble region of the piano, and this results in nonuniformity in tones of the entire scale.

Although the metal frame connected to the braces also contributes to the generation of a high tonal sound because of the fact that the vibrations of the braces are transmitted thereto, the vibrations of the braces are not sufficiently transmitted to the metal frame due to the attenuation of vibrations between them since the metal frame is secured to the braces by screws received in screw holes formed in the upper surfaces of the braces.

Accordingly the primary object of this invention is to provide an improved grand piano construction wherein braces and associated wooden structure are so arranged as to be fully utilized for the transmission of vibrations.

Another object of this invention is to provide an improved grand piano construction wherein braces are so arranged that the vibrations of sounds over the entire scale can be uniformly distributed and transmitted.

Still another object of this invention is to provide a grand piano construction wherein the metals of braces and a treble side brace are selected such that the volume and quality of tones in the treble region which tend to have been insufiicient may be improved and also that the generation of sound by improving the volume and quality of higher harmonic components of bass tones may be improved.

A further object of this invention resides in the provision of a grand piano construction wherein the vibration transmitting characteristic between a metal frame and braces is improved, thus generating sounds of sufiicient volume and of excellent quality.

These and other objects of this invention may be under stood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of one embodiment of a grand piano with a sounding board, etc. removed to illustrate the arrangement of braces in accordance with this invention;

FIG. 2 is a plan view of the embodiment shown in FIG. 1;

FIG. 3 is a plan view illustrating a sounding board and a metal frame mounted above the braces shown in FIG. 1;

FIG. 4 is a perspective view, partly broken away, taken along line IV-IV in FIG. 3; and

FIG. 5 is a view similar to FIG. 4, showing another example of the connection of the brace and the metal frame according to this invention.

Referring to FIGS. 1 and 2 illustrating the arrangement of braces of a grand piano in accordance with this invention, an inner rim 1 which substantially defines the shape of the piano has a cross block 2 which is connected at both ends to said inner rim 1 at portions somewhat inwardly retracted from the ends of the rim. One end of radially extending braces 3, 4, 5, and 6 is reinforcedly supported by metal fitting 7 and connected thereby to cross block 2 at a position slightly left of the central portion thereof (the bass side of the piano). The other ends of said braces are extending and connected to the inner surface of the inner rim 1. Between a slightly right-hand side portion of the cross block 2 with respect to the central portion thereof and the brace 6 located most righthand sidedly in the figure is securedly extended a brace 8 for the treble region of the piano.

A beam 9 extends obliquely from the inner left-hand side surface of the inner rim 1 to a portion close to the right-hand end of the cross block 2, so that the beam may intersect the braces 3, 4, 5, 6 and 8 approximately at central portions of the lengths thereof and form a fiat upper surface when the beam 9 is fitted into recesses formed in the respective braces at such intersecting portions. Preferably the beam may be rigidly secured to the braces by means of an adhesive and/ or screw threaded bolts. Usually, the braces consist of a wooden square rod which is 65 mm. in width and mm. in height, respectively, and the beam consists of a wooden board having a width of 65 mm., a thickness of 15 mm. It is most desired that the beam 9 is arranged to pass or intersect all the braces at their intermediate points as near to central points as possible of length, since when the braces are vibrated due to the vibrations of piano stirngs the amplitude of vibration is maximum at the central portions thereof so that the beam 9 connected to such central or intermediate portions is capable of most effectively transmitting the vibrations to the other braces. It has been found that the transmission of vibrations can be most efiiciently carried out when the beam is made of a hard wooden material, such as birch, hickory or maple.

A grand piano of the above mentioned wooden frame construction will have such an excellent sound effect that every sound of the scale of the piano can be balanced in volume and quality with any other sound of the scale. This effect may be attained by the action of the beam 9 connected to the braces 3, 4, 5, 6 and 8 by intersecting substantially central points thereof and which beam uniformly distributes vibrations including those of the sounds produced in the bass and middle regions and which are transmitted mainly to the four radially disposed braces, and those of the sound produced in the treble region of the piano and which are to be transmitted to the treble region brace 8. In addition, as already stated, the beam of the above arrangement is disposed obliquely with respect to the cross block and the inner rim, so that these components may form a triangular structure, which is considered to be very rigid in the sense of the theory of structures. In the conventional grand piano construction, the beam was arranged to lie in a direction parallel to the cross block within a space defined by the opposing portions of the inner rim, so that only a limited number of braces, say three, were connected to the beam, with the result that the vibrations of all the braces could not be balanced or averaged.

It has been found that with the braces of the above mentioned arrangement the volume and quality of the sounds of the treble region can be greatly improved when the treble region brace 8 is made of maple, birch, hickory or the like known as a hard wooden material. Heretofore it has been the practice to exclusively use beech for the braces for reasons of mechanical strength and assemblage. Such materials have a good transmission characteristic with reference to vibrations of the sound (several hundred cycles per second) in the middle region of the piano, but they do not show a good result when transmitting vibrations of the sound (several thousand cycles per second) produced in the treble region. Thus, the vibrations of the sounds in the treble region having less vibratory energy are not sufficiently transmitted to the braces or the metal frame, there being a tendency that the sounds of the treble region are weak when compared with those in the bass and middle regions. In accordance with the piano construction of the invention wherein a hard wooden material is employed as the treble region brace, the vibrations of treble sounds can be transmitted through the beam to the braces of the other regions and to the inner rim, thus generating treble sounds of sufiicient volume and ample quality and further improving the sound generation of higher harmonic components of bass tones. It is believed that before this invention no attempts had ever been made to discuss the material of the braces in the light of acoustics. According to this invention, it has been experimentally found that while maple is the most suitable material for the treble region brace and the beam 9, birch and hickory as well serve to remarkably improve treble sounds.

FIG. 3 shows a plan of a sounding board and a metal frame which are disposed above braces which are used in a middle size grand piano and are arranged in the manner similar to that shown in FIG. 1. The sounding board 11 is secured above the braces with a small spacing therebetween and the metal frame 12 is disposed above said sounding board 11. The metal frame 12 is rigidly secured at its peripheral portion to an inner rim 1 by means of screw threaded bolts 13 in such a manner that it will not contact the sounding board 11 and a bridge 14 bonded on the sounding board. The metal frame 12 is further connected to the treble region brace 8 (as shown in FIG. 1) by a bolt which penterates through a hole formed in the sounding board 11.

The manner of connecting the metal frame 12 and the brace 8 in the above example is shown in detail in FIG. 4. As shown, on one side surface of the treble region brace 8 is rigidly secured a metallic bolt receiving member 15 by a bonding agent and/or screw threaded bolts 16, the bolt receiving member 15 having a threaded bore extending substantially in a vertical direction.

FIG. 5 illustrates a modification of the bolt receiving member. This modified structure is substantially identical with that shown in FIG. 4 with the only exception that the bolt receiving member 19 is secured on the upper surface of the treble region brace 8.

One or a plurality of the bolt receiving members may similarly be placed at suitable places of the cross block and the braces including the treble region brace and connected to the metal frame 12 by bolts 17. The receiving members acting on the treble region are preferably metallic ones while wooden members should preferably be used for the bass and middle regions. In either case the bolts are closely engaged with the inner threaded surface of the bore formed in the receiving member, the connection between the wooden structure and the metal frame can be positively maintained without being loosened under the influence of temperature and/ or humidity. Unintentional relative rotation of the bolt receiving member and the bolt may be more positively prevented, if necessary, by adopting a further nut on the bolt in order to firmly couple the bolt and the bolt for receiving member which structure is usually called the lock nut structure.

While the invention has been disclosed with reference to the particular structure herein shown, it is not confined to the details and arrangement set forth, and this application is intended to cover such modifications or departures as may become within the scope of the appended olaims.

What is claimed is:

1. A grand piano construction including an inner rim, a cross block connected within said inner rim, a plurality of braces, and a metal frame, said construction comprising a beam extending from the inner surface of said inner rim to said cross block and connected to said braces while intersecting them nearly at central portions thereof.

2. The construction as claimed in claim 1 wherein said metal frame is connected to said cross block by a bolt receiving member and a bolt secured on the latter.

3. The construction as claimed in claim 1 wherein said metal frame is connected to said braces by a bolt receiving member and a bolt secured on the latter.

4. The construction as claimed in claim 1 wherein one of said braces which is located in the treble region of the piano is made of a wooden material harder than that of the other of said braces.

5. The construction as claimed in claim 4 wherein said wooden material is selected from the group consisting of maple, birch and hickory.

References Cited UNITED STATES PATENTS 204,106 5/1878 Steinway 84--l86 1,026,466 5/1912 Sc'hWamb 84-186 RICHARD B. WILKINSON, Primary Examiner.

LAWRENCE R. FRANKLIN, Assistant Examiner. 

1. A GRAND PIANO CONSTRUCTION INCLUDING AN INNER RIM, A CROSS BLOCK CONNECTED WITHIN SAID INNER RIM, A PLURALITY OF BRACES, AND A METAL FRAME, SAID CONSTRUCTION COMPRISING A BEAM EXTENDING FROM THE INNER SURFACE OF SAID INNER RIM TO SAID CROSS BLOCK AND CONNECTED TO SAID BRACES WHILE INTERSECTING THEM NEARLY AT CENTRAL PORTIONS THEREOF. 